Modern vehicles, such as aircraft, have an increasing number of antennas on them. Conventional communications systems utilize a point-to-point system using coaxial cable to connect radio receivers and transmitters to antennas and can be high loss, heavy and high volume systems. Additionally such systems can emit electromagnetic interference (EMI), which can cause reduced data integrity and increased error rates on transmission signals. Conventional communications systems must utilize great care to shield those signals from sources of electromagnetic radiation.
Optical communication systems have many advantages over systems that transmit electrical signals. Optical signals are immune to electromagnetic radiation and do not require shielding during transmission. Additionally, electrical signals can be transmitted for only relatively small distances because electrical signals incur losses proportional to the distance. Radio frequency signal losses increase rapidly as frequency increases. Optical signals, on the other hand, can be transmitted for great distances with little or no loss. Further, optical systems can reduce the amount of wiring required and can reduce the weight of the communication system. For these and other reasons, many communication systems incorporate optical signals and utilize optical networks.
Wavelength division multiplexing (WDM) can be used in optical networks to transmit many signals simultaneously over a single fiber by encoding them in different wavelengths or channels. An optical network can be bi-directional and permit a plurality of different network topologies. Optical bus interface modules can be used with the optical network that operate as a passive fiber optic coupler, which can be combined with WDM to selectively route optical signals in and out of the optical network at each node.
Conventional optical communication systems can be limited in transmitting radio frequency (RF) signals and other analog signals encoded with a high degree of information. Conventional optical communication systems are typically low power systems and the transmission of RF signals through an electronic device, such as an antenna, can require high power. Thus, conventional optical connections to an antenna have typically required a power amplifier at the antenna location on the vehicle, such as an aircraft. This can causes problems due to the heat generated by the power amplifier near the exterior of the aircraft.